Technical Field
The present disclosure relates to a phase detector, a motor drive controller using the phase detector, a motor apparatus using the motor drive controller, a sheet feeder using the motor apparatus, and a method of detecting phase.
Description of the Related Art
A technology of detecting the rotation phase of a rotor is known. Such a technology is used for controlling the rotation position of a motor, in particular, for a stop control of a brushless direct current (DC) motor. As an example, a rotary encoder method is known. In this method, a rotary encoder is connected to a rotation shaft, which is used to detect the relative rotation angle based on a biphase pulse signal having a phase difference that is variable according to the rotation phase.
The rotary encoder method is generally expensive due to the use of additional parts: a circular disc having optical window slits on its outer periphery at regular intervals and two photointerrupters arranged at a ¼ interval of the slit interval.